Dermatology > Demodicosis > Flashcards

Demodicosis Flashcards

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1
Q

What is demodicosis?

A
  • Inflammatory skin disease caused by the follicular mite Demodex canis
  • Disease state where the mites are prsent in much larger numbers
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2
Q

Where is Demodex canis usually found?

A
  • Normal habitant of skin/hair follicles generally found in small numbers in healthy animals
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3
Q

Is Demodex canis contagious?

A
  • No
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4
Q

is Demodex canis pruritic?

A
  • Not considered pruritic, but it can cause pruritus
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5
Q

Where does Demodex spend its entire life?

A
  • On the skin of the host
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6
Q

Where is Demodex typically found on the skin of the host?

A
  • Hair follicles and occasionally in the sebaceous glands
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7
Q

What are the life stages of Demodex (and # of legs for each)?

A
  1. Fusiform eggs
  2. Six-legged larvae
  3. Eight-legged nymphs
  4. Eight-legged adults
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8
Q

How long is the life cycle for Demodex?

A
  • 20-35 days
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9
Q

How are Demodex mites transmitted?

A
  • Spread from bitch to puppies in the first 3 days after birth
  • Nursing provides direct contact for transmission
  • Not transmitted or considered very difficult to transfer to dogs older than a few days old
  • Mites are not found in puppies born via C-section and raised away from the mother (i.e. in utero transmission does not occur)
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10
Q

Why do demodex mites proliferate in some dogs (juvenile onset generalized disease)?

A
  • Gene defect that is considered hereditary

- Thought to be autosomal recessive

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11
Q

What is thought to be underlying cause of generalized demodicosis in adults (and could be juveniles too)?

A
  • Probably T-cell defect
  • Somehow a depressed immune system
  • Think disease or drugs!
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12
Q

Predisposing factors for demodicosis

A
  • Age
  • Breed
  • Poor nutrition
  • Estrus
  • Parturition
  • Ectoparasites
  • Stress
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13
Q

Clinical lesions of demodicosis?

A
  • Alopecia (patchy/moth-eaten to complete)
  • Erythema
  • Comedomes
  • Papules
  • Pustules
  • Crusts
  • Draining tracts
  • Epidermal collarettes
  • Nodules
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14
Q

What are the two variants of demodex?

A
  • D. cornei (D. canis)

- D. injai

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15
Q

Is demodicosis easy to cure?

A
  • No

- OWNER FRUSTRATION IS BIG

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16
Q

What do demodex mites feed off of?

A
  • Follicular cells
  • Sebum
  • Epidermal debris
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17
Q

What can cause the pruritus with demodex?

A
  • Secondary pyoderma

- Possible hypersensitivity

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18
Q

Does D. canis survive off the host?

A
  • No
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19
Q

Differentials for folliculitis?

A
  • Demodex
  • Bacterial pyoderma
  • Dermatophytosis
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20
Q

What happens when demodex causes hair follicles to rupture or get irritated?

A
  • Folliculitis and furunculosis –> deep pyoderma

- Secondary pyoderma develops

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21
Q

How do you categorize demodex?

A
  • Localized vs generalized

- If generalized, juvenile onset vs adult onset

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22
Q

Localized demodicosis clinical signs

A
  • 1 to several areas
  • Patchy alopecia
  • Erythema
  • Scales
  • No to minimal pruritus
  • Face, forelegs
  • Usually 6 or fewer indicates localized; greater than 12 is indicative of generalized disease
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23
Q

Demodectic pododermatitis

A
  • Can be present on the feet of dogs without generalized lesions
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24
Q

When is the juvenile onset for localized democisosis?

A
  • Typically 3-6 months of age (<1 year usually)
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25
Cause of juvenile onset for localized democisosis?
- Immature immune system possibly
26
Progression of juvenile onset for localized democisosis?
- Rarely progresses to generalized form | - Up to 90% spontaneously heal without treatment
27
Treatment of juvenile onset for localized democisosis?
- Again, up to 90% spontaneously heal without treatment
28
Is juvenile onset for localized democisosis a genetic defect?
- Not generally, if it resolves
29
How quickly can hair re-grow for juvenile onset for localized democisosis?
Usually within 30 days
30
Clinical sites that can be affected for democisosis
- Face - Periocular area - Commissures of the mouth - Forelegs - Trunk - Rear legs - Paws (demodectic pododermatitis) - Bilateral ceruminous otitis
31
Do we treat localized form of demodicosis with miticidal drugs, and why or why not?
- NO because you need to see if it will progress if you are planning on breeding the dog - If it does progress, that would be an indication that you shouldn't breed this dog - Unless they are spayed or neutered and don't have to see if it's going to resolve or not
32
Monitoring and treatment for localized demodicosis
- Wait and monitor monthly - If it resolves, no genetic defect - If it progresses to generalized, then there is a genetic defect and the animal should not be bred
33
When does juvenile generalized demodicosis present?
- Starts <18 months of age
34
What characterizes juvenile generalized demodicosis?
- Many localized lesions (maybe greater than 6-12) | - Involves head, trunk, leg, 2+ feet
35
Juvenile generalized demodicosis clinical signs
- Large aras of alopecia - Erythema - crusts - Papules - Hyperpigmentation - Comedomes - Pustules - Epidermal collarettes
36
Clinical signs of concurrent pyoderma?
- Papules, pustules, epidermal collaretteS - Crusts, exudate - Pain - Pruritus - Lymphadenopathy - Systemic illness - Sepsis
37
Generalized demodicosis pododermatitis - What is involved? - How to diagnose? - Complications?
- may have feet involvement - Usually complicated by secondary infections - Can occur with body lesions - Difficult to scrape and treat (may consider hair plucks)
38
Where should you scrape for demodicosis?
- Scrape at the comedomes
39
Summary of the features of juvenile onset generalized demodicosis
- Starts as localized - <1 year age - GENETIC predisposition - Hence, DO NOT BREED these animals
40
When does adult onset generalized demodicosis tend to occur?
- Usually >4.5 years | - Rare
41
What diagnostic test should you run on all old dogs with pyoderma?
- Skin scraping
42
What should you look for with older dogs with generalized demodicosis?
- UNDERLYING DISEASE OR DRUGS - e.g. hypothyroidism, iatrogenic HAC, neoplasia, etc. - >50% have no underlying cause
43
What underlying diseases can contribute to generalized democisosis in adults?
- Excessive corticosteroid use - Endocrinopathies (hyperadrenocorticism or hpothyroidism) - Parasitism - Neoplasia - Poor nutrition
44
What diagnostics should be run for adult generalized demodicosis?
- CBC/Chem/UA - Heartworm and fecal checks - T4/TSH - ACTH stim or LDDST - Radiographs +/- U/S for neoplasia
45
Why should you look for underlying disease with adult generalized demodicosis?
- You're more likely to be successful if you find and treat the underlying disease
46
What drugs can contribute to generalized democisosis in adults?
- Apoquel - Prednisone - Chemotherapeutics
47
What are the two primary methods to diagnose demodex?
- Skin scrapings (multiple) - Hair plucks - Could also do a fecal float
48
Equipment needed for skin scrapings?
- #10 blade - Mineral oil - Slides and cover - Microscope
49
Where do you perform hair plucks?
- Near eyes and feet
50
Sensitivity of hair plucks compared to skin scrapings?
- About 50%
51
How do you perform skin scrapings?
- Want blood on your blade - Squeeze affected skin to extrude mites from hair follicles - Minimum of 3 scrapes from lesional skin
52
Microscope tricks to view demodex?
- 10x objective and lower your condenser
53
Where do you perform skin scrapings ideally?
- Scrape over comedomes
54
What would histopathology findings show with generalized demodicosis?
- Folliculitis/furunculosis +/- mites
55
Which breeds may need a biopsy to diagnose demodicosis?
- Chinese Shar Peis, Old English sheepdogs, Scottish terriers - May require a biopsy to diagnose demodicosis
56
What should you never use to treat demodicosis?
- CORTICOSTEROIDS
57
How to treat secondary bacterial pyoderma for localized disease (either intact or spayed animals)?
- Oral antibiotics - Topical treatment (2-4% chlorhexidine or Mupirocin ointment) - Benzyl peroxide (follicular flushing properties and antibacterial/anti-staph properties) - Gel or shampoo, but shampoo is drying
58
Goodwinol ointment for treating localized demodicosis?
- don't use
59
General treatment principles for localized demodicosis
1. Optimize health (improve nutrition and deworm) 2. Treat secondary pyoderma (oral antibiotics and topical treatments like benzoyl peroxide or chlorhexidine) 3. Recheck dog and rescrape in 3-4 weeks
60
What % of dogs with localized demodicosis will progress?
10% progress to generalized form 90% improve without treatment
61
Should you use miticidal drugs for localized demodex?
- No, you should not
62
Treatment options for generalized demodicosis?
- Weekly Mitaban (Amitraz dips) - Daily oral ivermectin - Daily oral milbemycin (interceptor) - Imidocloprid with moxidectin (advantage multi) which is weekly to biweekly - Isoxazolines
63
Golden rule for length of treatment for generalized disease?
- TREAT ONE MONTH BEYOND 2 negative skin scrapings one month apart
64
Amitraz drug class
- Inhibits monoamine oxidase (MAOI) and prostaglandin synthesis - Alpha-2 adrenergic agonist
65
What is labeled treatment for amitraz, and what is actually effective?
- Approved is every two weeks | - Weekly dips have increased efficacy
66
Amitraz/mitaban side effects
- Sedation - Disorientation - Bradycardia - Ataxia - Hypothermia - Vomiting/diarrhea - Pruritus - Hyperglycemia
67
Antidotes for mitaban/amitraz if overdosed?
- Yohimbine | - Antisedan
68
What is the only licensed treatment for demodicosis?
- Amitraz or Mitaban dips
69
How to use Amitraz or Mitaban?
- Use every week - Mix 1 vial in 2 gallons water - Sponge on entire mixture of product on patient - Let animal drip dry - Use half dose in small dogs
70
In which cases should you avoid Mitaban/Amitraz?
- Sedated animals because it can impact HR - Deep pyoderma - Diabetics (affects BG) - Small dogs (use half strength) - Concurrent use of Anipryl, amitriptyline, clompramine (MAO inhibitor) - Concurrent use of hydroxyzine
71
Drug class of ivermectin?
- Macrocyclic lactone
72
MOA of ivermectin
- Potentiates GABA gated chloride channels
73
WHich solution of ivermectin should you use and how should it be given?
- Bovine/equine injectable product - Oral dose daily - Use loading schedule to monitor for side effects
74
Is ivermectin for demodicosis on or off-label?
- OFF
75
Which breeds shouldn't get ivermectin and why?
- Collies and shelties - Australian shepherds - Old English sheepdogs - White feet, don't treat - MDR1 mutation can lead to accumulation and neurotoxicity
76
Which drugs should not be combined with ivermectin?
- Milbemycin - Selamectin - Mitaban - Ketoconazole
77
MDR1 gene mutation
- Abnormal P-glycoprotein pumps in blood brain barrier (typically responsible for pumping out the ivermectin) - Ivermectin accumulates in neurons, and neuro signs develop
78
Side effects of ivermectin
- Mydriasis - Anorexia - Ataxia - Tremors - Seizures - Coma - Death
79
What do you need to make sure about your patient before giving milbemycin oxime or ivermectin?
- Make sure they are negative for heartworm disease
80
Milbemycin oxime (interceptor) drug class
- Macrocyclic lactone
81
Milbemycin oxime - mechanism of action?
- Similar to ivermectin
82
Dose of milbemycin for demodicosis relative to the dose of milbemycin for heartworm?
- MUCH higher dose than for heartworm prevention
83
Relative safety of milbemycin oxime for herding dogs?
- Generally safer
84
Cost of milbemycin oxime
- Expensive
85
Side effects of milbemycin?
- Neurologic side effects like tremors and ataxia | - Start with 1 mg/kg and increase in 1 month if not responding (no change in mite count)
86
Drugs that shouldn't be used with milbemycin?
- Mitaban - Ivermectin - Selamectin
87
What is the treatment of choice for generalized demodicosis? Is it on or off label?
- Isoxazolines | - These are off label
88
MOA of isoxazolines
- Inhibit GABA and glutamate gated chloride channels
89
Efficacy of isoxazolines
- VERY effective
90
Isoxazoline safety in herding dogs?
- Safe in MDR1 +
91
Are isoxazolines insecticidal or acaricidal?
- They are BOTH
92
Which dose of isoxazolines should you use?
- Intended labeled dosage
93
Available products of isoxazolines
- Bravecto - Simparica - Nexgard - Credelio
94
How long does Bravecto last?
- 3 months
95
Which isoxazolines are safe for dogs with food allergies?
- Bravecto (hydrolyzed pork) - Simparica (hydrolyzed soy) - Nexgard and Credelio are not
96
Frequency of administration for Bravecto vs Simparica vs Nexgard vs Credelio
- Bravecto is 90 days | - All the others are every 28-30 days
97
Bravecto use in dogs under 6 months of age
- He wouldn't hesitate to use, but in theory the puppy might outgrow the dosage within 3 months
98
What are five keys to success with treating generalized demodicosis?
1. Use of isoxazolines (Bravecto and others) 2. Minimum of three months of therapy (USUALLY longer) 3. Avoid steroids (alters immune system and likely worsens clinical signs) 4. Spay or neuter 5. Treat secondary pyoderma
99
How long to treat generalized demodicosis?
- Minimum of three months | - Treat one month beyond 2 negative skin scrapings that are one month apart
100
Monitoring while treating generalized demodicosis?
- Monthly scrapes - CLinical cure BEFORE parasitologic cure! - Historical treatments could take months to get a negative scrape - Isoxazolines are very effective - Negative scrapes ON YEAR after last treatment
101
WHat are you evaluating durning monthly skin scrapings?
- Ratios of live to dead mites - Immature to mature - Look for eggs - Evaluate overall clinical picture and responsive
102
Prognosis for generalized form
- Guarded for complete cure unless you can find an underlying cause of disease - Excellent for clinical improvement and quality of life especially with isoxazolines - May need lifelong therapy - DO NOT breed juvenile onset generalized demodicosis
103
What should be avoided for generalized demodicosis for the life of the patient?
- Avoid steroids lifelong if possible - Avoid other immune-modulatory, anti-itch treatments like Apoquel and Atopica - Unless no other drug options exist or a medical emergency occurs
104
What is considered a clinical cure for generalized demodicosis?
- Considered cured if no clinical signs and mites are found 1 year after discontinuing treatment
105
Appearance of Demodex injai
- Long bodied mite
106
Where does D. injai live?
- Follicular mite that also lives in sebaceous glands
107
Where is D. injai found?
- Usually occurs or is found along the dorsum
108
Clinical signs of D. injai
- Seborrhea oleosa (greasy dermatitis) is a common clinical sign +/- alopecia
109
What breeds get D. injai?
- Typically terriers
110
Treatment of D. injai
- Treat like D. canis
111
Appearance of Demodex cornei?
- Short-bodied mite, basically D. canis (PCR)
112
Clinical signs of D. cornei
- May be pruritic, otherwise like D. canis
113
Treatment of D. cornei
- Treat like D. canis
114
What does MDR-1 code for?
- P-glycoprotein
115
Which drugs are concerning with MDR-1 gene?
- Ivermectin - Loperamide - Vincristine - Doxorubicin - Digoxin
116
How to test for ivermectin sensitivity?
- Cheek swab, $60 per test
117
What are the three types of feline demodicosis?
- Demodex cati - Demodex gatoi - Unnamed species
118
How common is Demodex cati?
- Rare
119
Is D. cati contagious or pruritic?
- Not contagious | - Not considered pruritic
120
What forms of demodicosis can occur with D. cati?
- Either localized or generalized
121
Which form (generalized/localized) is more common with D. cati?
- LOCALIZED
122
Where does localized demodicosis usually occur with cats?
- Nose, periocular skin, neck | - 1 to several small areas
123
Signs associated with localized demodicosis in cats
- Alopecia - Erythema - Crusting - Variable pruritus - Hyperpigmentation - Ceruminous otitis
124
Generalized form of D. cati - clinical signs and location?
- Same clinical signs | - Head, neck, trunk, limbs
125
What concurrent diseases can cause generalized D. cati?
- FeLV/FIV - Diabetes mellitus - Neoplasia - Hyperadrenocorticism - Toxoplasmosis
126
Dfdx for D. cati in cats
- Dermatophyte - Pyoderma - Causes of miliary dermatitis
127
What is highest on the list for causes of folliculitis in cats?
- Dermatophyte! | - Pyoderma and demodicosis are both rarer
128
Diagnosis of generalized demodicosis in cats
- Underlying disease search (minimum data base, FeLV/FIV, fecal, radiographs) - Skin scraping
129
Treatment for localized demodicosis in cats
- May be self limiting - Isoxazolines (Bravecto) - Lime-sulfur dips
130
Generalized disease treatments for demodicosis in cats
- Isoxazolines (Bravecto) - Lime sulfur - Amitraz - Ivermectin
131
How long to do lime sulfur dips for generalized demodicosis in cats
- Weekly until 1 month past negative scrapes
132
Ivermectin in cats adverse effects
- Can cause toxiciity
133
Mitaban in cats adverse effects
- Can cause ptyalism and sedation
134
Prognosis for generalized D. cati treatment
- Depends on ability to treat underlying disease
135
What does ceruminous otitis look like in cats (i.e. clinical signs)?
- Dirty ears | - Pruritus possible
136
Treatment for ceruminous otitis secondary to Demodex in cats?
- Topical ear mite treatments like Tresaderm
137
How id Demodex gatoi different from other demodex mites?
- SUPERFICIAL MITE (lives in stratum corneum) - PRURITIC - CONTAGIOUS - Short fat body
138
Appearance of Demodex gatoi
- Short, fat body
139
Is D. gatoi contagious?
- Yes
140
Is D. gatoi pruritic?
- Yes
141
Where is Demodex gatoi?
- In the stratum corneum
142
State distribution of D. gatoi?
Gulf states
143
Clinical signs with D. gatoi?
- PRURITUS*** - Alopecia - Excoriations - Crusting
144
Where on the body does D. gatoi tend to be?
- Head - Neck - Rear limbs - Flanks - Abdomen
145
Dfdx for D. gatoi
- Allergies - Psychogenic alopecia - Feline scabes (notoedric mange)
146
Diagnosis of D. gatoi in cats
- BROAD superficial scrapings - Scrape other cats - Treatment trial - Fecal**
147
What objective should you use to find D. gatoi?
- 10x and LOWER CONDENSER
148
Treatment for D. gatoi?
- TREAT ALL CATS - Lime sulfur dips for 6 weekly dips minimum - Improvement sometimes seen after 3 dips but may take as long as 12-15 weeks - Maybe Bravecto might help!
Dermatology
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